Today’s Brief Commentary
I’m writing this on the afternoon of December 10, the first full day of Q2B Silicon Valley in Santa Clara. Today’s news links have a few items from last week, more world leadership, which I have highlighted, and important news from Infleqtion/NVIDIA and Google.
Infleqtion has now demonstrated logical qubits via NVIDIA’s CUDA-Q quantum software development platform. Their target application is a materials science experiment, and all such quantum demonstrations are experiments at this point. This result shows more good progress for the neutral atom qubit approach, as well as another win for NVIDIA in the use of its open-source framework. Vendors supporting frameworks such as Cirq, Pennylane, and Qiskit should take note of this.
Google’s announcement of its new Willow quantum processing unit (QPU) created quite a buzz at Q2B this morning, but I sense it is now dying down. To me, the key is that it is a critical advancement in using the quantum surface error-correcting code. Although the paper was published in Nature yesterday, it has been available on arXiv for 3 ½ months. I link to it below. There’s some marketing fodder around a septillion years, but frankly, I don’t care how long it takes to benchmark some useless problem. Also, the surface code is not the newest one that people use, and we will likely deploy multiple kinds of codes within and among QPUs.
So, is there anything to Google’s announcement? Yes, of course. They have demonstrated excellent hardware control toward eventual large-scale error correction. What must they do next? Three things: 1) start showing progress on a practical problem that people care about, 2) show that they can network their QPUs because they are a factor of a thousand below the number of qubits that we will need, and 3) demonstrate that they can scale to a thousand or more physical qubits.
As a bonus, they could put Willow systems up on the Google Cloud so others can use and benchmark them.
Financial and Earnings Announcements
Italian VC operator CDP Venture Capital invests in Multiverse Computing as part of Series A round
(Thursday, November 27, 2014) “Multiverse Computing, a global leader in value-based quantum and quantum-inspired AI software solutions, today announced an investment from the largest Italian investor in venture capital CDP Venture Capital Sgr, as part of the company’s Series A round. The investment was carried out through two compartments of the Corporate Partners I fund, ServiceTech and Energytech, a corporate venture capital fund participated by some of the main Italian corporates as limited partners, including Baker Hughes, BNL BNP Paribas, Edison, GPI, Italgas, Snam and Terna Forward. Financial details of the investment were not disclosed.”
Newsletter Editions
A Quantum Computing Glossary
https://open.substack.com/pub/russfein/p/a-quantum-computing-glossary
Author: Russ Fein
(Friday, December 6, 2024) “… I hope many of these definitions help you in your efforts to understand and appreciate QC, and I have grouped them into silos to add context (although some may naturally apply to more than one silo). This is not intended to be a complete list, and it’s likely that more definitions will need to be added over time, but this should provide a good grounding in the general nomenclature and principles.”
Quantum Computing
Advancing hybrid quantum computing research with Amazon Braket and NVIDIA CUDA-Q | AWS Quantum Technologies Blog
Authors: Stefan Natu; Katharine Hyatt; Bettina Heim; Efrat Shabtai; Pradnya Khalate; and Tim Chen
(Wednesday, December 4, 2024) “Best of all, customers can now execute their CUDA-Q programs on all the quantum hardware backends supported by Braket, like the gate-based processors from IonQ, IQM, and Rigetti, and the analog quantum hardware from QuEra, simply by changing a single line of code.”
China Introduces 504-Qubit Superconducting Chip | The Quantum Insider
https://thequantuminsider.com/2024/12/06/china-introduces-504-qubit-superconducting-chip/
Author: Matt Swayne
Commentary:
A Forrester analyst asked me an interesting question once: how to you verify that a quantum computer really has as many physical qubits as it claims? I park this comment here, but it is an interesting general question, especially for small numbers of qubits that could be simulated in software.(Friday, December 6, 2024) “The development of the “Tianyan-504” sets a new domestic record, surpassing the 500-qubit threshold—a measure of the computer’s capacity to process quantum information, according to the statement. Quantum computers, unlike traditional computers, use quantum bits, or qubits, which can exist in multiple probabilistic states that theoretically allows them to tackle certain task faster than their classical counterparts. This could allow them, for example, the capabilities to outperform classical machines in certain calculations required for tasks, such as cryptography, material simulation and optimization problems.”
Oxford Ionics Partners with Quanscient and Airbus to Develop Quantum Solutions for CFD
Commentary: This is an important potential application area for quantum computing that is not discussed nearly enough.
(Friday, December 6, 2024) “Oxford Ionics, a world leader in trapped-ion quantum computing, today announced it is working together with Quanscient, a leading provider of multiphysics simulation software, and aerospace manufacturer Airbus to develop quantum simulations for computational fluid dynamics.
Used across a wide range of sectors, computational fluid dynamics (CFD) is a branch of fluid mechanics where computers simulate, analyze, and predict how fluids move. For the aerospace industry, CFD is used to predict the performance of aircraft including its lift, drag, noise, structural load capacity, and fuel efficiency.”
Infleqtion Delivers First Quantum Material Design Application Powered by Logical Qubits and NVIDIA CUDA-Q
(Monday, December 9, 2024) “Logical qubits are encoded in a collection of physical qubits, carefully orchestrated to mitigate errors. Though challenging to create and maintain, logical qubits are essential for practical quantum computing. By using logical qubits, Infleqtion’s demonstration paves the way for quantum computing solutions to complex problems, such as the development of more efficient batteries and the discovery of high-temperature superconductors. The accomplishment highlights the unique capability of Infleqtion’s neutral atom quantum platform, which supports custom arrangements of qubit connections to optimize algorithm efficiency.”
Meet Willow, our state-of-the-art quantum chip | Google
https://blog.google/technology/research/google-willow-quantum-chip/
Author: Hartmut Neven
(Monday, December 9, 2024) “Today in Nature, we published results showing that the more qubits we use in Willow, the more we reduce errors, and the more quantum the system becomes. We tested ever-larger arrays of physical qubits, scaling up from a grid of 3×3 encoded qubits, to a grid of 5×5, to a grid of 7×7 — and each time, using our latest advances in quantum error correction, we were able to cut the error rate in half. In other words, we achieved an exponential reduction in the error rate. This historic accomplishment is known in the field as “below threshold” — being able to drive errors down while scaling up the number of qubits. You must demonstrate being below threshold to show real progress on error correction, and this has been an outstanding challenge since quantum error correction was introduced by Peter Shor in 1995.”
Google claims quantum computing milestone — but the tech can’t solve real-world problems yet | CNBC
Author: Arjun Kharpal
(Tuesday, December 10, 2024) ““Google’s Willow chip has demonstrated a new milestone in how quantum computers can deal with errors that happen during their operation,” according to Winfried Hensinger, professor of quantum technologies at the University of Sussex. …
But despite optimism that quantum computing could one day change the world — or at least computers’ role in it — experts in the field have suggested that Google’s quantum computing breakthrough is still lacking in real-world uses.”
NVIDIA CUDA-Q Runs Breakthrough Logical Qubit Application on Infleqtion QPU | NVIDIA Technical Blog
Authors: Bharath Thotakura; Tom Noel; Pranav Gokhale; and Mark Wolf
(Tuesday, December 10, 2024) “Infleqtion, a world leader in neutral atom quantum computing, used the NVIDIA CUDA-Q platform to first simulate, and then orchestrate the first-ever demonstration of a material science experiment on logical qubits, on their Sqale physical quantum processing unit (QPU).”
Quantum Computing | Technical
A quantum engineer’s guide to superconducting qubits
https://pubs.aip.org/aip/apr/article/6/2/021318/570326/A-quantum-engineer-s-guide-to-superconducting
Authors: P. Krantz; M. Kjaergaard; F. Yan; T. P. Orlando; S. Gustavsson; and W. D. Oliver
(Wednesday, June 19, 2019) “The aim of this review is to provide quantum engineers with an introductory guide to the central concepts and challenges in the rapidly accelerating field of superconducting quantum circuits. Over the past twenty years, the field has matured from a predominantly basic research endeavor to a one that increasingly explores the engineering of larger-scale superconducting quantum systems. Here, we review several foundational elements—qubit design, noise properties, qubit control, and readout techniques—developed during this period, bridging fundamental concepts in circuit quantum electrodynamics and contemporary, state-of-the-art applications in gate-model quantum computation.”
[2408.13687] Quantum error correction below the surface code threshold
https://arxiv.org/abs/2408.13687
Authors: Acharya, Rajeev; Aghababaie-Beni, Laleh; Aleiner, Igor; Andersen, Trond I.; Ansmann, Markus; Arute, Frank; Arya, Kunal; Asfaw, Abraham; Astrakhantsev, Nikita; ; …; and Zobrist, Nicholas
(Saturday, August 24, 2024) “Quantum error correction provides a path to reach practical quantum computing by combining multiple physical qubits into a logical qubit, where the logical error rate is suppressed exponentially as more qubits are added. However, this exponential suppression only occurs if the physical error rate is below a critical threshold. In this work, we present two surface code memories operating below this threshold: a distance-7 code and a distance-5 code integrated with a real-time decoder. The logical error rate of our larger quantum memory is suppressed by a factor of Λ = 2.14 ± 0.02 when increasing the code distance by two, culminating in a 101-qubit distance-7 code with 0.143% ± 0.003% error per cycle of error correction. This logical memory is also beyond break-even, exceeding its best physical qubit‘s lifetime by a factor of 2.4 ± 0.3. We maintain below-threshold performance when decoding in real time, achieving an average decoder latency of 63 μs at distance-5 up to a million cycles, with a cycle time of 1.1 μs. To probe the limits of our error-correction performance, we run repetition codes up to distance-29 and find that logical performance is limited by rare correlated error events occurring approximately once every hour, or 3 × 109 cycles. Our results present device performance that, if scaled, could realize the operational requirements of large scale fault-tolerant quantum algorithms.”
